261420210 has 160 divisors (see below), whose sum is σ = 752716800. Its totient is φ = 64955520.

The previous prime is 261420199. The next prime is 261420233. The reversal of 261420210 is 12024162.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 728011 + ... + 728369.

It is an arithmetic number, because the mean of its divisors is an integer number (4704480).

Almost surely, 2^261420210 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261420210, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (376358400).

261420210 is an abundant number, since it is smaller than the sum of its proper divisors (491296590).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261420210 is a wasteful number, since it uses less digits than its factorization.

261420210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 438 (or 429 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 261420210 is about 16168.4943640402. The cubic root of 261420210 is about 639.4104352528.

Adding to 261420210 its reverse (12024162), we get a palindrome (273444372).

The spelling of 261420210 in words is "two hundred sixty-one million, four hundred twenty thousand, two hundred ten".